  PGPsendmail is a drop-in wrapper for the standard  sendmail
programme which resides as  /usr/lib/sendmail  on most Unix systems.
It allows the automatic encryption of outgoing messages by using the
recipient's PGP public keys. It does *not* provide for automatic
decryption of incoming messages: such a feature would necessarily
involve compromising your passphrase.
However, it can provide for automatic signing of outgoing messages by
using PGPdaemon.
